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DOE OSTI2023

Temperature dependence of magnetic anisotropy and magnetoelasticity from classical spin-lattice calculations

Here we present a classical molecular-spin dynamics (MSD) methodology that enables accurate computations of the temperature dependence of the magnetocrystalline anisotropy as well as magnetoelastic properties of magnetic materials. The nonmagnetic interactions are accounted for by a spectral neighbor analysis potential (SNAP) machine-learned interatomic potential, whereas the magnetoelastic contributions are accounted for using a combination of an extended Heisenberg Hamiltonian and a Néel pair interaction model, representing both the exchange interaction and spin-orbit-coupling effects, respectively. All magnetoelastic potential components are parameterized using a combination of first-principles and experimental data. Our framework is applied to the α phase of iron. Initial testing of our MSD model is done using a 0 K parametrization of the Néel interaction model. After this, we examine how individual Néel parameters impact the $B$ 1 and $B$ 2 magnetostrictive coefficients using a moment-independent δ sensitivity analysis. The results from this study are then used to initialize a genetic algorithm optimization which explores the Néel parameter phase space and tries to minimize the error in the B 1 and B 2 magnetostrictive coefficients in the range of 0–1200 K. Our results show that while both the 0 K and genetic algorithm optimized parametrization provide good experimental agreement for $B$ 1 and $B$ 2 , only the genetic algorithm optimized results can capture the second peak in the $B$ 1 magnetostrictive coefficient which occurs near approximately 800 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2018

Optimization of hot workability and microstructure control in a 12Cr-10Ni precipitation hardenable stainless steel: An approach using processing maps

Highlights: • Deformation processing map was developed for a 12Cr10Ni precipitation hardenable martensitic stainless steel and optimized hot working parameters were suggested to obtain defect free products. • The ‘stable’ domain of the processing maps were correlated to the dynamic recrystallization in the austenite phase and further confirmed by detailed microstructural investigations. • The DRx domain showed a refinement of the martensite packet size and of the prior transformation austenite grain size, essential to obtain the desired mechanical properties. - Abstract: Optimization of hot working parameters and corresponding microstructure control were explored in a 12Cr-10Ni precipitation hardenable martensitic stainless steel. From hot compression tests, 1073–1373 K (800°–1100 °C) and five (0.001–10 s{sup −1}) different strain rates, processing maps were developed, and various domains of microstructure evolution (in the austenite phase) were identified. The stable domain of the processing maps appeared to indicate dynamic recrystallization (DRx) in the austenite phase: as evident by the appearance of inflection point in the strain hardening rate versus flow stress plots. The suspected DRx domain was further confirmed by detailed microstructural investigations of the respective water-quenched specimens. The DRx domain showed a refinement of the martensite packet size and of the prior transformation austenite grain size. The later was shown with optical microstructure and reconstructed (modelled) microtexture data of the prior austenite grains. Additionally, the DRx domain showed a significant difference in activation energy as estimated from appropriate constitutive modelling.

36 MATERIALS SCIENCE↗

DOE OSTI2023

The Internal Compound Parabolic Concentrator (ICPC): a Novel Low Cost Solar Thermal Collection System for Desalination Processes

The research team at UC Merced designed, prototyped, and tested (1) a novel low cost non-tracking solar thermal collector/concentrator called the Integrated Compound Parabolic Concentrator (ICPC) and (2) a low-cost phase-change thermal energy storage system. Together these technologies can significantly reduce the levelized cost of heat from solar thermal sources while also incorporating features of dispatchability and portability. The ICPC allows elevated temperature and efficiency in a low cost, non-tracking collector. The collector has demonstrated 60% ±4% solar to thermal modules efficiency at fluid outlet temperature of 120°C. The raw material cost of the collector system is reduced by utilizing low cost aluminum minichannels. The collector design is also amenable to economic mass production. A 200 tube, 10 kW prototype array was constructed and tested, yielding over 6 kWh/day on average at outlet fluid temperature exceeding 120°C.

14 SOLAR ENERGY↗

DOE OSTI2020

Effects of Testosterone Supplementation on Ghrelin and Appetite During and After Severe Energy Deficit in Healthy Men

Abstract Background Severe energy deficits cause interrelated reductions in testosterone and fat free mass. Testosterone supplementation may mitigate those decrements, but could also reduce circulating concentrations of the orexigenic hormone ghrelin, thereby exacerbating energy deficit by suppressing appetite. Objective To determine whether testosterone supplementation during severe energy deficit influences fasting and postprandial ghrelin concentrations and appetite. Design and methods Secondary analysis of a randomized, double-blind trial that determined the effects of testosterone supplementation on body composition changes during and following severe energy deficit in nonobese, eugonadal men. Phase 1 (PRE-ED): 14-day run-in; phase 2: 28 days, 55% energy deficit with 200 mg testosterone enanthate weekly (TEST; n = 24) or placebo (PLA; n = 26); phase 3: free-living until body mass recovered (end-of-study; EOS). Fasting and postprandial acyl ghrelin and des-acyl ghrelin concentrations and appetite were secondary outcomes measured during the final week of each phase. Results Fasting acyl ghrelin concentrations, and postprandial acyl and des-acyl ghrelin concentrations increased in PLA during energy deficit then returned to PRE-ED values by EOS, but did not change in TEST (phase-by-group, P < 0.05). Correlations between changes in free testosterone and changes in fasting acyl ghrelin concentrations during energy deficit (ρ = -0.42, P = 0.003) and body mass recovery (ρ = -0.38; P = 0.01) were not mediated by changes in body mass or body composition. Transient increases in appetite during energy deficit were not affected by testosterone treatment. Conclusions Testosterone supplementation during short-term, severe energy deficit in healthy men prevents deficit-induced increases in circulating ghrelin without blunting concomitant increases in appetite. Clinical Trials Registration www.clinicaltrials.gov NCT02734238 (registered 12 April 2016).

Karl, J. Philip↗

DOE OSTI2025

Trigger-System Development for the HGCAL Cassette Testing (Final Report, Summer Internship 2023)

The Large Hadron Collider (LHC) will be upgraded to increase the instantaneous luminosity, which will result in an increase in the number of collisions from the 15 pile-up events of the first run of phase 1 to the 150-200 pile-up events of phase 2. Increasing the number of collisions means increasing the amount of radiation that the experiments will absorb. To meet these challenging conditions, the CMS calorimeters need to be upgraded. The new version of the hadronic HGCAL (High Granularity CALorimeters) in the endcaps will be assembled and tested in Fermilab’s laboratory. This report describes the new trigger system for testing the HGCAL’s cassettes.

42 ENGINEERING↗

DOE OSTI2025

Synthesis and Lithium Storage Properties of Spinel (Al 0.2 Mn 0.2 Co 0.2 Ni 0.2 Zn 0.2 ) 3 O 4 High-Entropy Oxide

High-entropy oxides (HEOs) have garnered significant interest as next-generation anode materials for lithium-ion batteries (LIBs) due to their high theoretical specific capacity and excellent structural stability. This study successfully synthesized spinel-structured (Al 0.2 Mn 0.2 Co 0.2 Ni 0.2 Zn 0.2 ) 3 O 4 HEO via a sol–gel method. The material was characterized by XRD, Raman and TEM, confirming a homogeneous single-phase spinel structure, with uniformly distributed elements-a hallmark of HEOs. Electrochemical tests demonstrated a stable cycling performance (438 mAh g −1 at 100 mA g −1 after 100 cycles and 350 mAh g −1 at 1 A g −1 after 1000 cycles) and rate capacity of 159 mAh g −1 at 2 A g −1 , The remarkable long-term cyclability and good rate capability highlight the potential of this HEO for practical applications in durable, high-power lithium-ion batteries. This work underscores the advantage of incorporating structurally stabilizing elements in HEOs for advanced energy storage.

anode materials↗

DOE OSTI2020

Development of Two-Phase Dense Fluid Expander for Advanced Cryogenic Air Separation and Low-Grade Heat Recovery

Cryogenic air separation represents the state-of-the-art technology to produce oxygen to feed coal gasification units. Given the maturity of this technology, it is difficult to identify opportunities to improve process efficiency and reduce the cost of the oxygen produced. However, Air Products conducted research and a feasibility investigation into the use of a two-phase (liquid-vapor) dense fluid expander (DFE) to improve the overall efficiency of cryogenic air separation. Demonstration of this novel concept was intended to allow two important process improvements: 1) elimination of the need for the DFE discharge to be single phase 2) expansion of the operating region of expanders in ASU service. Expanding the scope of turboexpander application beyond current application limits and traditional device designs would allow an increase in power recovery, and application of refrigeration and power recovery at new locations in process cycles would also enable the implementation of new process concepts. These new process concepts include power recovery from compression waste heat and refrigeration extraction and power recovery by replacing let-down valves with two-phase DFEs. Considering the maturity of cryogenic air separation, these new process options could represent a step change in power reduction and provide significant savings in operating costs. These new concepts would be particularly well-suited to large-scale oxygen production by cryogenic air separation and would enhance the economics of producing oxygen for use in coal gasification processes. Rotoflow, an Air Products business unit, manufactures dense fluid expanders in Pennsylvania for sites around the world. This project was executed in two phases, which are illustrated in Figure 1 below. Phase 1 consisted of a feasibility investigation of multiple applications of two-phase DFEs. In Phase 2, devices were identified, designed, fabricated and tested to explore the feasibility of commercial applications of DFEs operating in two-phase service. Engineering and testing were performed by personnel in Air Products’ Rotoflow business unit, with coordination with other Air Products business units.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2019

Effects of Sodium and Tungsten Promoters on Mg 6 MnO 8 -Based Core–Shell Redox Catalysts for Chemical Looping—Oxidative Dehydrogenation of Ethane

The present study investigates the effect of sodium and tungsten promoters on Mg 6 MnO 8 -based redox catalysts in a chemical looping oxidative dehydrogenation (CL-ODH) scheme. CL-ODH has the potential to significantly lower energy consumption and CO 2 /NO x emissions for ethylene production compared with conventional steam cracking. Sodium tungstate (Na 2 WO 4 ) was previously shown to be an effective promoter for Mg 6 MnO 8 -based redox catalysts. Overall, the CL-ODH reaction proceeds via parallel gas-phase cracking of ethane and selective combustion of H 2 on the surface of the Na 2 WO 4 -promoted redox catalyst. Reaction testing indicates that both Na and W are necessary to form Na 2 WO 4 and to achieve high ethylene selectivity. A Na:W ratio lower than 2:1 lead to significant formation of additional mixed tungsten oxide phases and decreases ethylene selectivity. Further characterizations based on low-energy ion scattering (LEIS) and differential scanning calorimetry (DSC) indicate that the NaW promoter forms a molten shell around the Mg6MnO8 redox catalyst. Methanol TPSR and in situ DRIFTS experiments indicate that the promoter significantly suppresses the number of basic sites on Mg 6 MnO 8 . 18 O– 16 O exchange experiments reveal that the promoter decreases the rate of oxygen exchange. O 2 cofeed studies indicate that below the melting temperature of Na 2 WO 4 , H 2 and CO conversions are both inhibited, but above the melting temperature, H 2 combustion significantly increased while CO combustion is still inhibited. On the basis of extensive characterizations, it was determined that H 2 is primarily combusted at the gas–Na 2 WO 4 molten shell interface via redox reactions of the tungsten salt, likely between the WO 4 2– (tungstate) and WO 3 – (tungsten bronze).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

CO 2 Hydrogenation: Na Doping Promotes CO and Hydrocarbon Formation over Ru/m-ZrO 2 at Elevated Pressures in Gas Phase Media

Sodium-promoted monoclinic zirconia supported ruthenium catalysts were tested for CO 2 hydrogenation at 20 bar and a H 2 :CO 2 ratio of 3:1. Although increasing sodium promotion, from 2.5% to 5% by weight, slightly decreased CO 2 conversion (14% to 10%), it doubled the selectivity to both CO (~36% to ~71%) and chain growth products (~4% to ~8%) remarkably and reduced the methane selectivity by two-thirds (~60% to ~21%). For CO 2 hydrogenation during in situ DRIFTS under atmospheric pressure, it was revealed that Na increases the catalyst basicity and suppresses the reactivity of Ru sites. Higher basicity facilitates CO 2 adsorption, weakens the C–H bond of the formate intermediate promoting CO formation, and inhibits methanation occurring on ruthenium nanoparticle surfaces. The suppression of excessive hydrogenation increases the chain growth probability. Decelerated reduction during H 2 -TPR/TPR-MS and H 2 -TPR-EXAFS/XANES at the K-edge of ruthenium indicates that sodium is in contact with ruthenium. A comparison of the XANES spectra of unpromoted and Na-promoted catalysts after H 2 reduction showed no evidence of a promoting effect involving electron charge transfer.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Flow boiling of R134a in a large surface area microchannel array for high-flux laser diode cooling

Packaging high average power laser diode arrays that generate heat at an area average flux in excess of 1 kW·cm -2 is a significant engineering challenge. While liquid microchannel coolers have demonstrated up to 11.9 kW·cm -2 , two-phase microchannel array coolers have not achieved 1 kW cm -2 due to critical heat flux and flow instabilities. In the current study, flow boiling heat transfer was characterized by a 1 × 10 mm heated zone centered over a 5 × 10 mm array of 125 very small channels (45 × 200 μm) with R134a as the phase change fluid. The high aspect ratio channels (4.4:1) were manufactured using MEMS fabrication techniques, which yielded a large heat transfer surface area to volume ratio. A test facility was used to characterize the heat transfer performance of boiling R134a over a range of saturation temperatures (15°C to 25°C), mass fluxes (735-2230 kg·m -2 ·s -1 ), and heat duties (< 110.3 W). During the tests, the calculated outlet vapor quality exceeded 61%, and the base heat flux at the heater reached a maximum of 1.1 kW·cm -2 . The resulting average experimental flow boiling heat transfer coefficients are found to be as large a 13.4 kW·m -2 ·K -1 over the approximately 3 mm two-phase region, with an average uncertainty of ± 2.72%. A substantial amount of heat was spread downstream via the low thermal resistance silicon floor. Specifically, between 29.5% and 55.1% of the heat dissipated in the two-phase region was dissipated over the heater. Finally, the remaining heat dissipated in the two-phase region was dissipated in the 2 mm of channel downstream of the heater. This suggests that heat spreading from the hotspot played a vital role in dissipating the heat load.

42 ENGINEERING↗

DOE OSTI2016

Phased Development of Accident Tolerant Fue

The United States Department of Energy (U.S. DOE) Advanced Fuels Campaign (AFC) has adopted a three-phase approach for the development and eventual commercialization of enhanced, accident tolerant fuel (ATF) for light water reactors (LWRs). Extending from 2012 to 2016, AFC is currently coming to the end of Phase 1 research that has entailed Feasibility Assessment and Prioritization for a large number of proposed fuel systems (fuel and cladding) that could provide improved performance under accident conditions. Phase 1 activities will culminate with a prioritization of concepts for both near-term and long-term development based on the available experimental data and modeling predictions. This process will provide guidance to DOE on what concepts should be prioritized for investment in Phase 2 Development/Qualification activities based on technical performance improvements and probability of meeting the aggressive schedule to insert a lead fuel rod (LFR) in a commercial power reactor by 2022. While Phase 1 activities include small-scale fabrication work, materials characterization, and limited irradiation of samples, Phase 2 will require development teams to expand to industrial fabrication methods, conduct irradiation tests under more prototypic reactor conditions (i.e. in contact with reactor primary coolant at LWR conditions and in-pile transient testing), conduct additional characterization and post-irradiation examination, and develop a fuel performance code for the candidate ATF. Phase 2 will culminate in the insertion of an LFR (or lead fuel assembly) in a commercial power reactor. The Phase 3 Commercialization work will extend past 2022. Following post-irradiation examination of LFRs, partial-core reloads will be demonstrated. The commercialization phase will further entail the establishment of commercial fabrication capabilities and the transition of LWR cores to the new fuel. The three development phases described roughly correspond to the technology readiness levels (TRL) defined for nuclear fuel development. TRL 1–3 corresponds to the “proof-of-concept” stage (Phase 1), TRL 4–6 to “proof-of-principle” (Phase 2), and TRL 7–9 to “proof-of-performance” (Phase 3). This paper will provide an overview of the anticipated activities within each phase of development and will provide an update on the current ATF development status.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

Development of coatings for ultrasonic additive manufacturing sonotrode using laser direct metal deposition process

ORNL partnered with Fabrisonic, LLC to develop galling resistant hard facing coatings on sonotrodes used to fabricate 3D printed materials using ultrasonic additive manufacturing. The development and deployment of a coated sonotrode is expected to push the existing state of the art to facilitate the solidstate additive manufacturing of hard steels and titanium alloys. To this effect a structurally amorphous stainless steel material and cobalt chrome material were deposited on the sonotrode material. Both the deposits showed good adhesion to the substrate. The coatings made using the structurally amorphous steel materials showed cracking during the initial trials and cracking was eliminated by deposition on a preheated substrate. Both the coatings show hardness in excess of 600 HVN. Thus the phase 1 of this project has been used to identify suitable materials to use to coat the sonotrode. Despite the fact that successful deposits were obtained, the coatings need to be evaluated by performing detailed galling tests at various temperatures. In addition field tests are also necessary to test the stability of these coatings in a high cycle ultrasonic vibration mode. If awarded, phase 2 of the project would be used to optimize the composition of the deposit material to maximize galling resistance. The industrial partner would then use the coated sonotrode to fabricate builds made of austenitic stainless steel to test the viability of using a coated sonotrode.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Synthesis and Structural Characterization of Sb-Doped TiFe{sub 2}Sn Heusler Compounds

Ternary Heusler compounds form a numerous class of intermetallics, which include two families with general compositions ABC and AB{sub 2}C, usually referred to as half- and full-Heusler compounds, respectively. Given their tunable electronic properties, made possible by adjusting the chemical composition, these materials are currently considered for the possible use in sustainable technologies such as solar energy and thermoelectric conversion. According to theoretical predictions, Sb substitution in the TiFe{sub 2}Sn full-Heusler compound is thought to yield band structure modifications that should enhance the thermoelectric power factor. In this work, we tested the phase stability and the structural and microstructural properties of such heavily doped compounds. We synthesized polycrystalline TiFe{sub 2}Sn{sub 1−x}Sb{sub x} samples, with x = 0, 0.1, 0.2 and 1.0 by arc melting, followed by an annealing treatment. The structural characterization, performed by x-ray powder diffraction and microscopy analyses, confirmed the formation of the pseudo-ternary Heusler structure (cF16, Fm-3m, prototype: MnCu{sub 2}Al) in all samples, with only few percent amounts of secondary phases and only slight deviations from nominal stoichiometry. With increasing Sb substitution, we found a steady decrease in the lattice parameter, confirming that the replacement takes place at the Sn site. Quite unusually, the as-cast samples exhibited a higher lattice contraction than the annealed ones. The fully substituted x = 1.0 compound, again adopting the MnCu{sub 2}Al structure, does not form as stoichiometric phase and turned out to be strongly Fe deficient. The physical behavior at room temperature indicated that annealing with increasing temperature is beneficial for electrical and thermoelectrical transport. Moreover, we measured a slight improvement in electrical and thermoelectrical properties in the x = 0.1 sample and a suppression in the x = 0.2 sample, as compared to the undoped x = 0 sample.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Assessing mechanical response of CO 2 storage into a depleted carbonate reef using a site-scale geomechanical model calibrated with field tests and InSAR monitoring data

Geomechanical risks of injection have raised concerns regarding secure CO 2 storage. In this work, a combined monitoring and modeling approach is used to assess the stress changes and surface uplift associated with CO 2 injection into a depleted carbonate reef of the Michigan basin. A site-scale geomechanical model is built by assigning mechanical properties of formations using well-log and experimental data. Gravity load is applied to the model to estimate the vertical component of stress as well as different lateral boundary displacement scenarios to estimate horizontal stresses. We used a poroelastic pressure-dependent model (instead of a linear elastic mechanical earth model) to calibrate initial stresses using hydraulic fracture test data measured at depleted reservoir status. Multi-phase fluid flow-geomechanical simulations are performed to estimate the poroelastic response during (1) primary depletion (2) field-scale CO 2 injection phase (3) a hypothetical forecast scenario in which well bottom hole pressure (BHP) reach 45000 KPa. The predicted surface uplift is less than 1 mm at the end of the field-scale CO 2 injection phase which is in good agreement with Interferometric Synthetic Aperture Radar (InSAR) uplift measurement. Although the InSAR data shows an insignificant uplift, hydromechanical modeling of injection shows that CO 2 injection still causes reservoir deformation emphasizing the role of carbonate overburden and reservoir formation mechanical properties and limited size of reef on diminishing the surface deformation. Modeling indicates poroelastic response of caprock matters to estimate uplift. The lower permeability of the top two layers provides additional barrier to large uplift. Also, history of subsidence due to production should be accounted to predict uplift due to a follow up injection correctly. This report shows the significance of combining a calibrated geomechanical model with field measured stresses and monitoring data to be used as a tool to ensure the safety of CO 2 storage.

42 ENGINEERING↗

DOE OSTI2021

Radio frequency mixing modules for superconducting qubit room temperature control systems

As the number of qubits in nascent quantum processing units increases, the connectorized RF (radio frequency) analog circuits used in first generation experiments become exceedingly complex. The physical size, cost, and electrical failure rate all become limiting factors in the extensibility of control systems. We have developed a series of compact RF mixing boards to address this challenge by integrating I/Q quadrature mixing, intermediate frequency/LO (local oscillator)/RF power level adjustments, and direct current bias fine tuning on a 40 × 80 mm 2 four-layer printed circuit board with electromagnetic interference shielding. The RF mixing module is designed to work with RF and LO frequencies between 2.5 and 8.5 GHz. The typical image rejection and adjacent channel isolation are measured to be ~27 dBc and ~50 dB. By scanning the drive phase in a loopback test, the module short-term amplitude and phase linearity are typically measured to be 5 ×10 -4 (V pp /V mean ) and 1 ×10 -3 radian (pk-pk). The operation of the RF mixing board was validated by integrating it into the room temperature control system of a superconducting quantum processor and executing randomized benchmarking characterization of single and two qubit gates. We measured a single-qubit process infidelity of 9.3(3) × 10 -4 and a two-qubit process infidelity of 2.7(1) × 10 -2 .

47 OTHER INSTRUMENTATION↗

DOE OSTI2017

Centrifugal Contactor Efficiency Measurements

The contactor efficiency of a 2-cm acrylic centrifugal contactor, fabricated by ANL using 3D printer technology was measured by comparing a contactor test run to 5-min batch contacts. The aqueous phase was ~ 3 ppm depleted uranium in 3 M HNO3, and the organic phase was 1 M DAAP/dodecane. Sampling during the contactor run showed that equilibrium was achieved within < 3 minutes. The contactor efficiency at equilibrium was 95% to 100 %, depending on flowrate.

42 ENGINEERING↗

DOE OSTI2021

Measurement of internal dark current in a 17 GHz accelerator structure with an elliptical sidewall

A 17 GHz single cell, standing wave, copper accelerator structure with an axisymmetric elliptical central cell sidewall was tested for internal and downstream dark current as a function of gradient up to 93 MV/m. The elliptical sidewall was predicted to suppress the internal dark current and the lower order multipactor modes as compared with a previously tested structure having a straight sidewall. During the conditioning phase of the elliptical sidewall structure, strong internal dark current generated by an N = 1 multipactor mode was observed at gradients in the 10 to 20 MV/m range. After conditioning with 2.2x10^5 pulses to 93 MV/m, the N = 1 mode was completely suppressed and no multipactor resonances were observed. The internal dark current was reduced to a comparatively low level, much smaller than in the previously studied, straight sidewall structure, in good agreement with simulations. The energy spectrum of the electrons colliding with the sidewall was measured using an isolated side dark current monitor and a bias voltage. As the conditioning progressed, the electron energy spectrum showed an increase in the concentration of lower energy electrons, also in good agreement with simulations. Studies of internal dark current may help to understand the rf conditioning and ultimate performance of high gradient accelerator structures.

43 PARTICLE ACCELERATORS↗

DOE OSTI2018

Mechanical properties, deformation behavior and microstructure evolution of Ti-43Al-6Nb-1Mo-1Cr alloys

Highlights: • The alloys exhibit excellent high-temperature tensile properties. • Activation energy of deformation (Q) and n are 571 KJ/mol and 2.765, respectively. • The hot processing maps of strain 0.5 and 0.6 are displayed. • Phase transformations and microstructure evolution are explained in different conditions. • Three types of deformation mechanisms are exhibited at different temperature. - Abstract: The high-temperature properties, microstructure evolution and deformation behavior of a novel Ti-43Al-6Nb-1Mo-1Cr(at.%) alloy were studied in this paper. The ultimate tensile strength (UTS) and elongation (δ) were tested at 800, 850, and 900 °C, in which the excellent strength 551 MPa, 510 MPa, and 382 MPa, and elongation 2.9%, 12.7%, and 16.8% were exhibited, respectively. Isothermal compression tests were carried out in the temperature range of 1100–1250 °C and strain rate range of 0.001–1.0 s{sup − 1}. Based on dynamic materials model (DMM) and phase diagram, dynamic recrystallization mechanism and phase transformation during thermal deformation were clarified and the hot processing maps were calculated. The experimental results show that the values of stress exponent (n) and the apparent deformation activation energy (Q) of Ti-43Al-6Nb-1Mo-1Cr(at.%) were calculated to be 2.77 and 571 KJ/mol. Meanwhile, three various types of microstructure evolution in different deformation conditions were discussed and concluded.

36 MATERIALS SCIENCE↗